1. Field of the Invention
The present invention relates to a traction device for a ski base to enable greater control at a snow surface. Specifically, the invention pertains to a waxless ski base useful on cross-country skis and related winter sports equipment.
2. Prior Art
Like many forms of sport activity, cross-country skiing has now developed an individual identity as a sport requiring its own form of unique equipment and training. Although any ski could be used in cross-country activity, recent years have seen the development of a "waxless ski base" which is specifically adapted to enhance the traction of this ski base.
Cross-country skiing differs from down-hill skiing in that the participant frequently must navigate all types of terrain, including level and uphill grades. Obviously, some traction is desirable so that the skier can literally walk up a hill without removing his skis. Furthermore, in traversing level grades, the cross-country skier utilizes a "kicking" technique in which the skier pushes off against traction developed by the ski base of the cross-country ski.
Typically, this traction section of the ski base is referred to as the "kicking zone" and is located in the waist or midportion of the ski. Numerous methods have been applied to develop a traction configuration for use in the kicking zone. An example of such a device is illustrated in U.S. Pat. No. 1,989,377 by Osborn which shows a strip of material having a plurality of folds designed to engage the ski surface and operate as an attachable traction device.
Several mechanical equivalents have been developed since the osborn patent to accomplish the same objective. U.S. Pat. No. 3,927,896 and Swiss Pat. No. 253,733 disclose skis with cleat devices which operate to project below the surface of the ski to retard movement. Additional Swiss patents which have provided a more sophisticated mechanical approach to this problem include 213,007 and 340,748. The latter Swiss patents combine this traction surface as an integral part of the ski, with the capacity of adjusting into or out of a traction mode.
The Swiss 340,748 patent teches a ski base which can be modified from a flat configuration to a stepped configuration; however, there is little adjustability or variation to the projection pattern between the in and out adjustments. Furthermore, each traction pad is displaced an equal distance from the base of the ski such that the traction portion of the ski is a linear-type projection.
The Swiss 213,007 patent discloses a ski base cleat system which is not adjustable into a flat or glide base surface mode. Instead, the cleats are projected out of the base line in a convex displacement pattern in accordance with the displacement of a rubber strip which has the cleats attached thereto. This is displaced by a finger which can be rotated outward through the ski to place the cleats below the base line and thereby subject any rearward glide to the traction of such cleats.
Finally, the modern trend in cross-country skis is to premold a base with a permanent nonlinear gripping surface such as the Fishscale NOWAX ski marketed by TRAK. The base of this "fishscale" ski has a molded plastic configuration which resembles the scales of a fish and includes gliding surfaces which are slightly inclined away from the base to form a gripping or kicking edge toward the rear of the scale.
These various cross-country ski configurations each provide one or more benefits to the skier who desires improved traction for negotiation of hills or level terrain. However, none of these skis provide the versatility to permit the skier a broad range of adjustment from a flat-base configuration which operates similar to a down-hill ski, to a variety of cleat projections which are adapted for various snow and terrain conditions. This need of adjustment versatility is particularly critical in cross-country skiing because the cross-country skier does not restrict himself to a well groomed ski area which has had trees and other obstacles removed. To the contrary, the cross-country skier must be able to negotiate wilderness areas through forests and over snow which is unpacked and whose condition will vary during the course of a single day. Therefore, the variety of skiing conditions cannot be compared to a typical ski resort whose downhill terrain has been cleared and groomed, and whose snow condition is packed and controlled.
For example, the cross-country skier may start in the early morning and ski a crusted snow which requires a specific type of base adjustment. As the day progresses, those areas of snow exposed to the sunlight will soften, requiring a different base adjustment. In the forest areas, however, the crust may remain due to shading of the trees. Further adjustment may be desired where the cross-country skier negotiates deep powder as opposed to hard packed snow conditions.
In addition to these variety of snow conditions, adjustment versatility for the base of the cross-country ski is further required where the skier is a beginner versus an expert, or when the skiing is to be informal and leisurely as opposed to high performance competition.
To date, the prior art has simply not provided a ski whose versatility meets the demand of a broad spectrum of changing conditions. What is needed, therefore, is a single ski adapted for specific adjustment to unique conditions typically encountered by the cross-country skier.